Abstract: A computer-controlled push-door system was designed and tested as a method for measuring motivation. Eleven domestic hens were trained to use the push-door to gain access to food. They were deprived of food for 12 h or 43 h on 12 occasions and the push-door was used to measure the amount of “work” (measured as force × time) that they performed to gain access to a food reward. When deprived of food for 12 h the hens took significantly longer (P<0.01) to reach the required threshold of work, than when deprived for 43 h. This difference arose from the amount of time that the hens spent not pushing at the door. The problems encountered with this system and such an approach to measuring motivation are discussed.

Abstract: Przewalski's horses (Equus przewalskii) are believed to be extinct in the wild; the current known population of 797 animals exists wholly in zoos. The Species Survival Commission of the International Union for Conservation of Nature and Natural Resources is proposing to reintroduce this endangered species into its former Mongogian habitat within the next decade. Knowledge of the behavior of harem-forming equids in general and of Przewalski's horses in particular, is of great importance to the captive propagation and eventual reintroduction of this species. Horses are rarely solitary by nature. Solitary captive animals are prone to pacing. Juvenile male feral horses (Equus caballus) form bachelor herds upon dispersal from their natal band. Zoos can set up bachelor herds as a way of managing surplus males. The older, more dominant feral horse bachelors are the first to acquire mares. Bachelors do not generally obtain females until they are 4 or 5 years of age. The first females acquired are usually 1- and 2-year-old fillies dispersing from their natal band. Because of the age differential, the stallions are generally dominant to their mares. Behavioral impotence may result if captive stallions are given a harem at too young an age, especially if the harem contains older, more dominant, females. Typical harem sizes in the wild are 3-5 mares. Captive stallions with too large a harem may become either apathetic or aggressive toward their mares. Wild horses spend 60-70% of their time foraging. Captive animals may quickly consume their limited amounts of food and develop vices out of boredom. Provision of hay ad libitum reduces the amount of pacing seen in captive animals, and virtually eliminates coprophagy.

Abstract: Herding behavior in ungulates is executed mainly by males. There are several forms of herding: guarding a single estrous female; rounding up a bunch of females during the rutting season; territorial herding by which a male keeps females inside his territory; herding of a moving, permanent, harem group; social herding in which group members of both sexes are herded by one dominant male. When put into this sequence, a phenotypical trend is illustrated, leading from an intimate connection of herding with mating behavior toward an increasing independence from sexual behavior and culminating in a complete socialization of herding. Aspects and problems of herding behavior are the recognition of, and the animal's respect for, partners in gregarious species; the animal “taking offense” at activities of others which deviate from its own activity; the active coordination and synchronization of group activities; the use of, and the effects of, threat, dominance and courtship displays in herding; the possibility of substitution among expressive displays in relation to partners of different sex; the communicative function of the animal's orientation relative to the partner; social hierarchy and leadership in a group; the possibility of interspecific herding, particularly in man-animal relationships, which is closely linked to the process of domestication.

Abstract: Methods are described to assess horses' selective grazing ability that includes choosing, sorting and the adaptive value of this behaviour. Choosing ability was tested by the experimenter presenting pairs of cut plant species that were then alternated at each presentation until the test horse had taken three bites of one of the plant pair. The results were analysed in relation to five measures of choosing behaviour: (1) the strength of the choice; (2) correspondence between first bite and the final choice; (3) constancy of the choice over a number of trials; (4) the comparison of the horses' ranking of the species over a number of trials; (5) the constancy of the linear arrangement of the plants over a number of trials. Sorting ability was tested using two methods. A mixture of two plant species was presented either in a clamp or loose in a trough. Results were based on number and weight of plant residues. The adaptive value of the behaviour related to the bitterness of toxic plants. This bitterness was represented in testing by quinine sulphate and a poisonous Senecio species. An extremely bitter substance “Bitrex” was also used in this context but was totally accepted by the horses. The horses' reactions to these substances were monitored using a behavioural score chart. The results from 12 horses revealed that the horses differed individually in their grazing ability. On this basis, the horses were classified as efficient, semi-efficient, or inefficient grazers. This finding has practical implications in deciding which horses may safely graze on pastures infested with toxic plants.